Recovery and filtering apparatus and method



March 19, 1957 G. M. GLIDDEN RECOVERY AND FILTERING APPARATUS AND METHOD Filed Feb. 25, 1955 2 Sheets-Sheet l ATTURNE March 19, 1957 G. M. GLIDDEN RECOVERY AND F'ILTERING APPARATUS AND METHOD Filed Feb. 25, 1953 2 Sheets-Sheet 2 ATToRNEYs.

INVENTOR.'

BY WW,

United Sttes Patent i RECOVERY AND FILTERING APPARATUS AND NETHGD Galen M. Glidden, Wheaton, Ill., assigner to Acme Protection Equipment Company, Chicago, Ill., a partnership Application February 25, 1953, serial No. 338,638

2 Claims. (ci. 18s- 37) This invention relates to a'recovery and iiltering apparatus and method, and has especial utility in the Iecovery of noxious particulate material such as mercury drops in a directly usable'form without putting mercury particles or vapor into the surrounding air and while purging the air of mercury vapor.

Liquid mercury is used extensively in commercial processes, as for example the making of mercury thermometers, instruments, and in medicinal applications. It is a characteristic of such operations that mercury spillage onto the oors and tables, etc., is always present. The spillage is undesirable because it has heretofore resulted in the waste of the spilled mercury. Further, mercury is a relatively volatile material and when a small spill at room temperature is viewed by means of ultraviolet light and fluorescent screen the evaporation of mercury looks much like the smoke from a lighted cigarette held in the fingers. The vaporization is progressively greater as the temperature increases from the freezing point of mercury (negative 38 F.) to a temperature of 674.4 F. The equilibrium concentration at room temperature of 77 F. is over twenty milligrams per cubic meter and is double this amount at 93 F. The generally accepted maximum allowable concentration is 0.1 milligram of mercury per cubic meter of air, and it is seen therefore that mercury spillage must be quickly removed so that the maximum allowable concentration of mercury in the air is not exceeded. The removal of the mercury spillage is a matter of health, since mercury is noxious or harmful to humans. In acute cases of mercury poisoning, death has occurred.

Heretofore mercury spillage has been controlled by reducing the rapid production of vapor by spreading owers of sulphur on the spill. This has been followed by a cleanup and disposal of the sludge. This procedure is undesirable in that mercury is expensive and the spillage is lost. In addition, the mercury sludge formed with the owers of sulphur has to be handled during its disposal, which further increases the hazards to those disposing of the spillage. There has been a need for a better means of clearing areas of mercury spillage, while concurrent with this need is the desirability of providing therewith a means or method for recovering the spilled mercury in usable form.

It is therefore an object of this invention to provide apparatus and a method of recovering noxious material such as mercury spillage and to do so with safety to personnel. Another object of the invention is to clear an area of mercury spillage while at the same time recovering the mercury in a form ready for immediate reuse. Still another object of the invention is to recover mercury spillage while preventing mercury particles and mercury vapor from getting into the air as a result of ;the recovery process. A further object of the invention is the recovery of mercury spillage in usable form and at the same time the purging of the surrounding air of mer- 2,785,767 Patented Mar. 19, 1957 cury vapor. Yet a further object is that of recovering mercury spillage by using air from the surrounding atmosphe're in combination with a suction device while purging the air of mercury vapor by means of lters. Additional objects and advantages of the invention will appear as the specification proceeds.

An embodiment of my invention is illustrated in the accompanying drawings, in which- Figure l is a vertical sectional view taken through the center of the apparatus; Fig. 2 is a perspective view of the various parts of the apparatus in spaced-apart relation and in the order of their assembly; Fig. 3 is a cross-sectional view of the retainer and gasket; Fig. 4 is a transverse sectional view of the threaded portion ofthe lilter trap; Fig. 5 is a broken vertical sectional view of the threaded portion of the trap; and Fig. 6 is a perspective view of the snap-in threads.

It is seen in both Figs. l and 2 that my apparatus includes a container or body member 10 providing a chamber l1 therein. The container or casing 10 is equipped with a castor frame 12 carrying a plurality of spaced castors 13. At its upper end the casing 10 is equipped with a pair of handles 14 and in addition has pivotally mounted thereon hood clamps 15 that are used for securing the upper structure, that will be later described, upon the casing l0. The clamps 15 are well known and since they are conventional it is believed that a detailed discussion of these members is not necessary.

The side wall of the casing l@ is equipped with an inlet opening 16 having mounted thereabout an outwardly extending connector member 17 equipped with a threaded portion 17a and an annular flange 17b secured to the side Wall of the casing and providing a substantially air tight connection therewith. A pipe or conduit 1S having a threaded end portion is threadedly received upon the connector portion 17a and a gasket 13a provides a fluid tight seal therebetween. Mounted upon the pipe 18 is a trap 19 that comprises a casing structure 2li having an opening at the lower end thereof and being provided with a laterally or outwardly extending wall Zla about the opening and a peripheral wall 2Gb depending from the wall 20a. The enlarged opening thus provided is equipped with threads 2l adapted to receive the threaded neck of a jar or receptacle 2.2. The receptacle 22 may be, if desired, transparent so that the contents thereof are readily visible from the outside.

I prefer that the threads 2l be of a snap-in type construction so that they may be inserted into the end of casing 20 within the depending wall 2Gb after the trap has been fabricated and treated. The treatment, for example, may consist of porcelainizing the entire structure. The circular or helical wire thread illustrated best in Figs. 4 through 6 is suitable for this purpose and is equipped with outwardly-extending spaced-apart ears 21a that extend through appropriate apertures 2lb in the peripheral wall 2Gb. The ears support the thread and also provide appropriate support for a receptacle received therein. A gasket 22a is provided to seal the receptacle to the outwardly-extending wall 20a and thereby provide a lluid tight seal with the trap 19. I have found that in the operation of my device, as will be hereinafter described, the vacuum or negative pressure within the easing 20 and receptacle 22 draws the receptacle tightly against the gasket 22a and provides a liuid seal between the wall 20a and receptacle 22. A simple thread arrangement for supporting the receptacle will therefore suce and the yieldability of the wire 2i or the vertical movement of the wire permitted by the loose tit of the ears 21a within the apertures 2lb readily allow the ,receptacle to be drawn upwardly by the vacuum within the trap.

The trap i9 is provided with an inlet opening 23 through the side wall thereof that is spaced slightly below the outlet opening i6, and rigidly mounted in the opening 23 is a `pipe or conduit 24 having extended Aportions thatpenter the trap. Together the wportions of the `tubular conduits i@ and 24 thatV extend intothe trap i9 form arcuate or curved batiies that deflect air iiowing through the trap and provide a tortuous path that the air must follow. Both the pipe or conduit l and the conduit 24 may be welded to the casing portion 2@ of the trap so that an air tight hitting between the conduits and the trap lis attained.

The upper end of the casing 16 is open and the upper edge of the casing walls is rolled outwardly to provide an annular support 25 upon which is mounted a resilient retaining gasket 2 The gasket 25 may be made of rubber or some other similarV material. As seen best in Fig. 3, the gasket 26 is provided with an annular recess 27 .extending thereabout and an annular ange 28 that extends downwardly from the main portion of the gasket.

Y The annular flange 23 has an outer diameter substantially equal to the inner diameter of the Ycylindrical casing and fits snugly therein.

A filter frame 29 is equipped at its upper end with a laterally extending annular tlange 3? that is received within the recess 27 provided by the gasket 26 and is supported thereby in depending relation within the chamber 1i. The lter frame 2% is substantially open, with the exception of the ilange 30 and ring portion 31 formed integrally therewith, but is provided with a plurality of Vspaced apart U-shaped support members 32 vthat'are adapted to receive thereon a particle filter 33. Preferably the particle iilter 33 is a porous acid-resistant fabric and preferably a dustless fabric such as Dynel. The fabric filter 33 may be supported upon a wire frame 33a that is preferably made of stainlessrsteel, while the filter frame 29 is preferably porcelain enamel, although it may also be stainless steel or other non-corrosive material. The diameter of the upper edge'of the lter 33 and the wire support therefor may be such that it tightly engages the outer surface of the imperforate portion 31 of the filter frame above the VLJ-shaped members 32 and is drawn tightly thereover. The ends of the wire 33a may be twisted to tighten the'fabric about the frame 29. Y

A canister 34 that is preferably of stainless steel is Vequipped at its upper end with an'outwardly inclined truste-conical portion 35 having formed integrally therewith a laterally extending iiange 36 that is received within the recess 27 of the gasket 26. The bottom of the canister 34is provided with an inwardly extending support or ring 37 but `is otherwiseropen throughout the entire bottom area.

Within the canister 34 and resting upon the ,inwardly extending support 37 is a plate 38 equipped throughout with a plurality of apertures so that the plate oifers little resistance to the iiow of air therethrough. Resting upon the plate 38 is a wire screen 39 that may 'be Vof about No. l2 mesh. A lter material 4t? is received upon the wire screen 39 and is retained within the canister 34 by the side walls thereof. Above thefilter material 40 is a second wire screen 41 that is identical with the screen 39. A plurality of coil springs 42 are supported upon the upper surface of the screen lil and in turn support an upper perforated plate 43 that is somewhat larger in diameter about the canister and extend upwardly ltherefrom andV through spaced apertures adjacent the periphery of the upper plate 43. The nuts 44 draw the plate 43tightly against Ythe canister 34. This structure Yis effective to compress the filterv material 4l) within the canister and between the wire screens. The perforated plates38 and 43, the screens 39 and 41, springs 42, wing nuts 44 and studs 45 are preferably all made of stainless steel and the canister 34 is porcelain enamel or other non-corrosive material. This material is particularly acid-resistant and resists amalgamation with mercury. The iltermaterial 40 is preferably material Vthat will trap mercury vapor and free air passing through the lter from mercury vapor. l prefer toV use manganese dioxide impregnated with copper, which is sold and is known by the trade name Eopcalite. This material is granular and is highly porous and presents a very large karea while being'slowly penetrated by mercury vapor. The structure described provides for Ithe ready removal of the granular lilter material 40 from the canister and -this is desirable since periodic replacement is needed. l have found that after about 40 hours of operating my apparatus for recovering and ltering the air of mercury vapor, it is desirable to replace the filter material 40. The length of time that the filter material is effective to remove mercury vapor from the air will of course depend upon the concentration of mercury vapor in the air. Where the concentration is fairly heavy I have found that 40 hours is'a reasonable time for operationV of the apparatus before changing the filter material.

Supported upon the upper surface of the gasket 26 is an annular support member 46 that extends upwardly and inwardly and terminates in a substantially horizontal ring pontion 47. Rigidly secured to the horizontal portion 47 is an annular ring support 48 that rigidly carries at its inner side a circular channel support 49. The channel'support is extended inwardly at 50 and the inward extension is rigidly attached to a cylindrical ventical sup.-

' port member 51.V Depending from the vertical support member V51 and extending thereacrossto substantially seal the member is a shield 52 equipped centrally with an aperture and having an inner bifurcated edge 53. Mounted within the spaced legs of the bifurcated edge 53 is a bearing 54't`hat rotatably supports the shaft 55 of a motor 56. The shaft 55 extends Vdownwardly through the bearing 54 and'isV equipped with a pair of spaced hubs .57 and 58 that are provided respectively with blades 59 and 60 forming a centrifugal fan that is effective to suck air upwardly through the lilter members. The blades v59 and 60 are spaced apart, and interposed therebetween are stationaiy blades 61 rigidly carried by the downwardly extendingwall 62 of -a cover frameY 63. The wall 62 is mountedupon the channel member 49. Formed integrally with theV wall 62 is an inwardly extending plate 64 that terminates at its inner end adjacent the inner-ends of the blades 60 and at a spaced distance-from'the hub 58. Thus, air :drawn by the centrifugalfan through the lter untllows upwardly through the central aperture of the member 64 and is forced by the rotating andV stationary blades between the walls 62 and the shield 52 and upwardly through,k apertures 65 provided .through themember 50.

A cover66 secured at its lower end to theY member 46v extends upwardly therefrom and in spaced relation therewith and terminates in a substantially'horizontal portion 67 Vproviding anV annular opening therethrough. The upwardly and inwardly inclined walls of themember 66 are provided with a plurality of spaced aperturesz through which the air forced throughv the fan and through the apertures 65 must flow to be discharged to the atmos- 'phere A ring member 69 is secured to the wall 51 andY to the cover 66. YBoth the cover 66 and the linner member 46 are of relatively rigidrnaterial and together md in combination with the wall 5l support theV motor-56.` g

A cover 70 equipped with a plurality of spacedV disf charge ports 71 is provided Von itsinner vsurface, with 'Y a felt liner 72. The cover 70 encloses the upper por-Y tion of theV motor 56 that `extends vertically above the member 66-and the cover` 70 may be secured in -position Vupon the ring 69 by cap screws Yor other `comparable seuring means (not shown). Suitable struts or, other well known arrangements may be provided to stabilize the motor 56 and render the entire structureA as rigid as desired. Extending vertically above the cover 70 is a timer unit designated generally by the numeral 73. The timer mechanism is enclosed by a casing 74 that is provided adjacent its lower edge with a plurality of spaced apart apertures 75 suitable for the passage of air therethrough.

Any of the numerous and well known timing devices may be utilized to indicate the length of time that my apparatus is in actual operation. Preferably I employ a type of counter that is connected to the motor 56 and includes a dial 76 that indicates the total operating time numerically. Thus, by glancing at the dial 76 the operator knows the exact time that the apparatus has been in operation and when the filter material 40 has been in the machine for about 40 operating hours the workman will know that it is time to change the filter material. If desired, a dual reading may be provided; one reading will show the total operating time, while the second dial is adjustable so that it may be set to zero when a new filter material has been placed in the apparatus. Such devices are numerous `and well known and a detailed showing and description are believed unnecessary.

Since the recovery and filtering apparatus may be used for the recovery of mercury, it is desirable that the air used to pick up mercury droplets or particles and which will have a relatively high mercury vapor content not be drawn through the motor for the cooling thereof, the reason for this being that mercury drawn through the hot motor would readily amalgamate with the motor part-s and quickly cause a deterioration thereof. Therefore I have sealed the motor 56 from the lower structure by means of the closure member or shield S2 as previously described. To provide for cooling of the motor 56 a separate fan (not shown) is secured to the motor shaft 55 and serves to draw air through the apertures 75, through the motor, and to discharge the air through the apertures or discharge ports 71 in the side wall of the casing or cover 70.

Operation After the filter material 40 has been placed between the screens and plates in the canister 34 and secured therein as previously described, and the canister and fabric filter 33 are supported within the casing 10 by the gasket 26, the upper motor and fan assembly is placed upon the gasket 26 a-s illustrated in Fig. 1 and the clamps or fasteners are pivoted upwardly and drawn over the edge of the cover 65 which is equipped with an annular ring 77 to hold the fasteners 15 in position. The entire assembly thus provides a sealed unit and is ready for operation. A removable jar 22 is threaded into place to complete the trap 19 and upon the placing of suitable hoses and pickup tools, which are conventional and not shown, upon the outer end of the pipe 24 the motor 56 may be actuated by means of the usual on-oft switch. Though conventional in a design sense, the tools, etc., are made of plastic or other material that does not amalgamate with mercury.

The fan blades 59 and 6b are rotated rapidly by the motor 56 and air is drawn through the pickup tools and hoses and is sucked into the trap 19. The heavier mercury particles or droplets will impinge upon the side walls of the trap, and further, because of the ba'le arrangement resulting in a change in direction of the air flow, the heavier or larger particles will drop from the air stream and into the receptacle 22. The air stream will then pass through the pipe 18 and into the chamber 1i provided by the casing 10, where it will be drawn upwardly through the fabric filter 33. Any remaining large mercury particles and those being smaller in size will be intercepted by the fabric filter 33 and will cling thereto or will drop to the bottom of the chamber 11.

The air will be drawn upwardly through the filter ma` terial 49 by the centrifugal fans 59 and 60 and the filter material will remove mercury vapor from the air passing therethrough. The air will be expelled through the apertures 65 and finally through the apertures 68 and into the atmosphere in substantially mercury-free condition. These operations are continued until the area is clear of mercury spillage, and may be repeated as often as is necessary to remove mercury spillage from the iioors, tables, etc. After about 40 hours of operation the lter material 40 should be changed to insure the discharge of mercury-free air.

As a safeguard, the apparatus may be operated continuously with the pickup tubes removed. In such case, room air is sucked through the pipes 24 and 17 as previously described and the air purged of mercury vapor and discharged back into the atmosphere through the v apertures 68. Continuous operation in this manner may be advantageous where the concentration of mercury is particularly heavy and because of the evaporation of mercury as previously set out which soon renders the air unsuitable and noxious.

The mercury particles collected in the receptacle 22 are substantially free of contamination and may be immediately reused. If desired, the receptacle may be removed and capped for storage, or the mercury poured therefrom and into the usual storage containers.

Changing of the filter material 40 presents no problem, since the fasteners 15 may be released and the upper motor and fan assembly lifted from the gasket 26. The wing nuts 44 are then released and the upper plate 43 and wire screen 41 together with the springs 42 can be lifted from the filter material. If desired, the entire canister and fabric filter unit 33 can be lifted by means of the gasket 26 and the filter material 4t) poured therefrom into suitable discard containers. The fabric filter 33 can also be replaced at the same time. The canister is then refilled and the upper plate and screen secured in place by the wing nuts, While the springs compress the granular particles.

It will be apparent from the foregoing discussion that in addition to the apparatus described my invention includes the method of recovering mercury droplets and filtering the air. In the method a stream of air is maintained and the stream is passed over mercury particles, whereby the particles are picked up by the air stream. The air stream with the particles therein is passed through a devious path that is effective to remove the larger particles or droplets of mercury from the air stream. Subsequently the stream is passed through a filter that further removes mercury particles from the air and is also effective for removing mercury vapor from the air. The filtered air is then discharged.

While in the foregoing specification I have set forth an embodiment of my invention in substantial detail for purposes of illustration, it will be apparent to those skilled in the art that changes may be made in the details without departing from the spirit of the invention.

I claim:

l. Apparatus adapted to recover mercury spillage by means of air pickup and 4adapted to lter mercury vapor from the air, comprising a cylindrical casing providing a chamber therein and having an enlarged discharge opening in the top thereof, said casing having also an inlet opening in a wall thereof, a trap for collecting mercury particles and having an outlet port in open communication with said lchamber through said inlet opening, said trap providing an inlet port and being equipped with curved bafiies interposed between the inlet and outlet ports, a particle filter extending :across said discharge opening and depending therefrom, a canister mounted above said particle filter and being enclosed thereby, said canister being open at its bottom and having mounted thereon a bifurcated plate, a screen above said plate, filter material consisting of granular particles above said screen, a second screen above said til-ter material, plate and securing means for holding said filter material within Vsaid Y 7 Va'nister, an suction means for drawing air through said trap, chamber and filters. y

2. The 'structure of claim 1, in whicha pair oftuhular conduits extend into said trap through the inlet and outlet ports thereof, andV in which said curved baies are provided by lthe end portions of said tubular conduits Y within'sad trap.

References Cited in the le of this patent UNITED STATES PATENTS 955,886 Laughlin Apr. 26, 1910 1,315,424 Schies Sept. 9, 1919 '1,422,211 Lamb July 11, 1922 1,665,602 Netherland Apr. 10, 1928 Sporer Dec. 10, 1929 Monso "et al. Jan. 13, 1931 Baker Oct. 4, 1932 Stoek- Dec. 11, 1934 Reutter Apr. 6, 1937 Holm-Hansen Oct. 11, 1938 Kraissl Ian. 24, 1939 Meyers Mar. 28, 1939 Spielman Oct. 29, 1940 Ramsey Dee. 16, 1941 FOREIGN PATENTS 

1. APPARATUS ADAPTED TO RECOVER MERCURY SPILLAGE BY MEANS OF AIR PICKUP AND ADAPTED TO FILTER MERCURY VAPOR FROM THE AIR, COMPRISING A CYLINDRICAL CASING PROVIDING A CHAMBER THEREIN AND HAVING AN ENLARGED DISCHARGE OPENING IN THE TOP THEREOF, SAID CASING HAVING ALSO AN INLET OPENING IN A WALL THEREOF, A TRAP FOR COLLECTING MERCURY PARTICLES AND HAVING AN OUTLET PORT IN OPEN COMMUNICATION WITH SAID CHAMBER THROUGH SAID INLET OPENING, SAID TRAP PROVIDING AN INLET PORT AND BEING EQUIPPED WITH CURVED BAFFLES INTERPOSED BETWEEN THE INLET AND OUTLET PORTS, A PARTICLE FILTER EXTENDING ACROSS SAID DISCHARGE OPENING AND DEPENDING THEREFROM, A CANISTER MOUNTED ABOVE SAID 